[objcmt] Introduce "objcmt-white-list-dir-path=" option.

This options accepts a path to a directory, collects the filenames of the files
it contains, and the migrator will only modify files with the same filename.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@194710 91177308-0d34-0410-b5e6-96231b3b80d8
11 files changed